Experimental plant for simultaneous production of 14N and 15N by 15N/14N exchange in NO,NO2–HNO3 system under pressure

An experimental study on ¹⁴N and ¹⁵N simultaneous separation using the chemical exchange in NO, NO₂–HNO₃ system under pressure is presented. The influence of the pressure and of the interstage 10 M HNO₃ flow rate on the separation of ¹⁴N and ¹⁵N was measured on a packed column with product and waste refluxers. At steady state and 1.8 atm (absolute), the isotopic concentration at the bottom of the separation column was 0.563 at% ¹⁵N, and in the top of the column was 0.159 at% ¹⁵N. The height equivalent to a theoretical plate and interstage 10 M HNO₃ flow rate values, obtained in these experimental conditions, allows the separation of ¹⁴N highly depleted of ¹⁵N and of ¹⁵N at 99 at% ¹⁵N concentration.     

Bestimmung der 15N-Häufigkeit von N2O und N2 mittels emissionsspektrometrischer continuous-flow-Messung

Abstract

Tests were made for a quantitative decomposition of N₂O to N₂ and for the setting of a statistical equilibrium in mixtures with gaseous nitrogen of nonrandom distribution by emission spectrometric continuous-flow-measurements. Under high-frequency-discharge conditions a residence time of 0.5 seconds is enough for a quantitative decomposition. In this time the statistical balance in the mixture of N₂O and N₂ is reached. The determination of the relative ¹⁵N abundance in pure N₂O or N₂ gases or in mixtures of N₂O and N₂ in a continuous-flow-emissionspectrometer can directly be achieved.     

15N16O的激光磁共振谱与同位素分子15N17O和15N18O的光谱分析

采用内腔式饱和吸收技术获得 Ｌａｍ ｂ 凹陷,使 Ｃ Ｏ 激光磁共振谱仪的灵敏度及分辨率大大提高．利用该技术对自然丰度下１５ Ｎ １６ Ｏ 的 Ｘ２Π（ υ＝ １） ← Ｘ２Π（ υ＝ ０） 塞曼跃迁进行测量,实现了包括Λ双分裂在内的各种精细结构的谱分辨．结合已发表的１５ Ｎ Ｏ 同位素分子光谱实验数据进行分析计算,拟合得到迄今最完备、最精确的各相关同位素分子１５ Ｎ ｍ Ｏ（ ｍ ＝ １６ —１８）的结构参数．     

15N-Markierung von Plasmaaminosäuren nach oraler Applikation von [15N]Glycin, [15N]Leucin und [15N]Hefeprotein-Thermitase-Hydrolysat

For the biosynthetic preparation of ¹⁴C-erucic acid (C₂₁H₄₁COOH) by means of rape plants cv. sollux the plants were supplied with ¹⁴CO₂ and additionally fed with ¹⁴C-Sodium acetate after anthesis. After saponification of the extracted lipids the erucic acid was isolated and purified. The substance was identified by gas chromatography. The incorporation of the applied radioactivity (34 MBq ¹⁴CO₂; 37 MBq¹⁴C-natrium acetate) into the fatty acids amounted to 1,2 per cent. The eruric acid could be isolated from the fatty acids mixture with a specific radioactivity of 1,001 MBq/mmol and a purity of 97,2 per cent.     

The 2CH excitation band in C2H2–N2O and 2CH+torsion combination bands in C2H2–N2O and C2H2–CO2

A preliminary analysis of the 2CH excitation band in C₂H₂–N₂O in the 1.5 µm range (K. Didriche, C. Lauzin, P. Macko, M. Herman and W.J. Lafferty, Chem. Phys. Letters 469, 35 (2009).), only considering 117 low J-, and K_a - vibration-rotation lines, is significantly extended thanks to the analysis of new spectra including very regular series of lines with J/K_a up to 31/15. 1271 b-type lines were assigned. Perturbations are briefly discussed. The rotational temperature in the experiments is estimated to be 20?K and the upper state mean half-time is 1.6?ns for non perturbed levels. The previous analyses of the 2CH + torsion band in C₂H₂–N₂O and in C₂H₂–CO₂ (C. Lauzin, K. Didriche, T. Földes and M. Herman, Mol. Phys. 109, 2105 (2011).), are also extended to include 286 and 234 lines, respectively, also correcting for calibration errors. New rotational constants are obtained using a rigid rotor Hamiltonian by simultaneously fitting the ground, 2CH and 2CH + torsion states in C₂H₂–N₂O, and the latter state, only, in C₂H₂–CO₂.     

[15N]Methacetin-und [15N]Ammoniumtest zur Leberfunktionsprüfung im Kindesalter

The stable isotope content of samples of precipitation and of the river water throughout the Piracicaba basin in Brazil was measured over a two-year period. The isotope values of precipitation follow a consistent pattern of relatively depleted values of both deuterium and oxygen 18 during the rainy summers and enriched ones during the dry winters, with all values aligned slightly above the Global Meteoric Water Line. The isotopic composition of the river water throughout the basin shows a remarkable spatial coherence and much smaller scatter of data than those of the precipitation. The isotope composition of river water is close to that of the precipitation in the rainy season, however, with a consistent lower d-excess value by 1‰–2‰. This is attributed to evaporative water loss in the basin, in part an expression of the recycling of water due to the anthropogenic activity in the region. The more divergent values are recorded during high-water stages in the rivers. In many cases, the floods during the beginning of the rainy season are characterized by an enrichment of the heavy isotopes and lower d-excess values when compared to the precipitation, with the opposite situation later in the rainy season. This is interpreted as resulting from the watershed/riverflow interaction pattern, and it thus suggests that the isotope composition can monitor the hydrologic situation in the basin and its changes.     

Dynamic modelling and simulation of 15N separation by chemical exchange in NO,NO2–HNO3 system

The dynamic behaviour of a ¹⁵N separation process by chemical exchange in a NO, NO₂–HNO₃ system has been analysed based on an accurate mathematical model. A nonlinear system of first-order partial differential equations was determined by considering the multiple exchange reactions between the components of the gaseous mixture and the liquid phase constituents. The mathematical model of the process describes the space–time variation of the ¹⁵N mole fraction in gas and liquid phases and provides a better understanding of operating limits and decision support in process design and optimisation.     

Ozone generation in air and N2 + O2 mixtures in wire-to-cylinder reactors – an optimization attempt

The experimental results obtained with a wire-to-cylinder ozone generator (5–20 cm in length, inner diameter 12mm), using a 5 to 60 l/h flow-rate range of air or N₂ + O₂ mixtures, a negative DC high voltage being applied to the wire, are analyzed.As for the classical industrial ozonizers, the chemical engineering method, based on the energy density concept (Becker parameter = P/Q) and the global coefficients of formation K _f and destruction K _d of ozone, was applied. Some peculiar behaviours of the K _f coefficient and the role played by nitrogen and its excited levels are pointed out. The results obtained are compared with those of other authors. It appears clearly that the main parameters are not only the Becker parameter but also, and independently, the applied electrical power (P) and gas flow rate (Q) through the residence time (t _r), acting on the temperature of the reactant gas inside the reactor. It seems that t _r needs to be higher than about some seconds.As with oxygen, an optimization of the ozone production in a wire-to-cylinder ozonizer can be founded on the economical criterion = /C ² or its inverse C. more directly measurable in the usual practice.     

PS-1 Optical Interconnection of 2N×2N Using N×N Holographic Lens Array

A method of N×N sub-array crisscross insertion has been put forward. N×N holographic lens array is used for realizing PS-1 optical interconnection of the 2N×2N element array. The condition for the sub-array interlacing was analyzed. The formula of the PS-1 imaging magnifying power and the imaging distance have been given for both parallel light illumination and divergent light illumination. The results indicated that the formula of the PS-1 imaging magnifying power and imaging distance realized by N×N sub-array crisscross insertion are identical with the results of the PS realized by 2×2 holographic lens array. The experiments prove correctness of the formula.     

Spatial variations in larch needle and soil δ15N at a forest–grassland boundary in northern Mongolia

The spatial patterns of plant and soil δ¹⁵N and associated processes in the N cycle were investigated at a forest–grassland boundary in northern Mongolia. Needles of Larix sibirica Ledeb. and soils collected from two study areas were analysed to calculate the differences in δ¹⁵N between needle and soil (Δδ¹⁵N). Δδ¹⁵N showed a clear variation, ranging from ?8?‰ in the forest to ?2?‰ in the grassland boundary, and corresponded to the accumulation of organic layer. In the forest, the separation of available N produced in the soil with ¹⁵N-depleted N uptake by larch and ¹⁵N-enriched N immobilization by microorganisms was proposed to cause large Δδ¹⁵N, whereas in the grassland boundary, small Δδ¹⁵N was explained by the transport of the most available N into larch. The divergence of available N between larch and microorganisms in the soil, and the accumulation of diverged N in the organic layer control the variation in Δδ¹⁵N.     

Soil δ15N patterns in old-growth forests of southern Chile as integrator for N-cycling

Old-growth forests of southern Chile represent an important reserve of temperate (rain) forests in the world. Wetter and colder forest ecosystems appear to be more efficient in conserving and recycling N such that mostly non-plant available N species are lost, which could be indicated by more depleted δ¹⁵N values of the soil and plants. Hydrological N loss from the old-growth forests in southern Chile occurs mainly via dissolved organic nitrogen and not via dissolved inorganic N. Forest disturbances (e.g. fire, clear-cutting or enhanced N deposition) cause (abrupt) changes in ecosystem N-cycling processes. In this study, we hypothesized that δ¹⁵N signatures of soil profiles under old-growth forests could be used as an integrator for ecosystem N-cycling, and changes of these δ¹⁵N profiles could be valuable to assess ecosystem resilience towards disturbances. Six old-growth forests were selected in the phytogeographical region of the Valdivian rain forest in southern Chile. One of the sites has been partly burned in February 2002. First, we observed that ecosystems with higher mean annual precipitation and lower mean annual temperature were relatively more depleted in ¹⁵N. Secondly, we found that a forest fire caused a 100-fold increase of the nitrate export and induced an enrichment of the soil δ¹⁵N signal in the upper 20 cm.     

Phenomenological separable potential of K + N interaction for J≤15/2

A nonlocal separable potential of K ⁺ N interaction in the isospin-0 and isospin-1 S, P, D, ..., J scattering channels is constructed. This potential describes satisfactorily the results of the SP92 phase-shift analysis (R. Arndt) at incident-kaon energies in the interval from 0 to 2.4 GeV. The off-shell amplitudes for kaon-nucleon scattering are calculated. They are shown to differ significantly from the commonly used off-shell amplitudes.     

SHA+脉冲序列用于g-C3N4样品15N-15N相关性的固体核磁共振研究

利用固体核磁共振实验研究了15N标记的g-C3N4样品中的15N-15N空间相关性,在高场和魔角旋转条件下对比两种不同的脉冲序列PDSD和SHA+的实验效果。发现当某个氮上连有质子的时候,脉冲序列SHA+比PDSD可以更好地检测15N原子间的极化转移。该研究可以为材料科学领域,特别是含氮掺杂的碳材料,提供一种有价值的研究方法。